Device for the print-referenced cutting of a printed web

ABSTRACT

A device for the print-referenced cutting of a printed web in which the effective circumference of a web feeding drum is slightly different from the print spacing, but can be increased or decreased, respectively by the selectively controlled approach motion of a counter roller against a depressible circumference portion of the drum, thereby advancing a longer or shorter web section. The approach motion is normally blocked by a solenoid controlled latch pin, the solenoid responding to a photoelectric cell.

[ 1 Aug. 19, 1975 [56] References Cited UNITED STATES PATENTS DEVICE FORTHE PRINT-REFERENCED CUTTING OF A PRINTED WEB [75] Inventor: OttoNiepmann,Gevelsberg,

Germany Primary Examiner-Frank T. Yost Attorney, Agent, or Firm.1osephA. Geiger & n n a y n .ma Nm 6 r FG e e .ma t mG 0 MC a m, 9 S A N 7[57] ABSTRACT A device for the print-referenced cutting of a printed[22] Filed: July 26, 1974 21 Appl. No.: 492,205

web in which the effective circumference of a web [30] ForeignApplication Priority Data feeding drum is slightly different from theprint spac- July 27, 1973 ing, but can be increased or decreased,respectively by the selectively controlled approach motion of aGermany............................ 2338109 counter roller against adepressible circumference [1.5. CI. portion of the drum therebyadvancing a longer or 83/366; 83/367; 83/371; 83/436; 226/28; shorterweb section. The approach motion is normally 226/19] blocked by asolenoid controlled latch pin, the sole- B65h 25/10 noid responding to aphotoelectric cell. 83/75, 72, 322, 365, 366,

[51] Int.

[58] Field of Search.........

14 Claims, 4 Drawing Figures PATENTEU Ans-1 9 I975 sum 1 [If 2 PATENTEDAUB1 91975 sum 2 BF 2 Fig.4

Fig 3 DEVICE FOR THE PRINT-REFERENCED CUTTING OF A PRINTED WEBBACKGROUND OF THE INVENTION l. Field of the Invention The presentinvention relates to devices for cutting a printed web of paper orplastic material into discrete lengths, and in particular to devices forthe printreferenced cutting of printed blanks for soft cigarettepackages, using a feed roller cooperating with a counter roller.

2. Description of the Prior Art Devices for unwinding a continuous webfrom a supply roll and for cutting it into a series of blanks are knownfrom the prior art. They feature a rotating feed drum with a cuttingknife arranged on its periphery, the feed drum cooperating with acounter roller for both the cutting operation and the web advancingaction.

Prior art devices of this kind, however, have the disadvantage ofproducing an invariable distance of web advance during each cuttingcycle, thereby allowing registration errors that may occur between theprinted patterns on the continuous web and the placement of the cut toaccumulate.

SUMMARY OF THE INVENTION It is an objective of the present invention tosuggest an improved device for the cutting of continuous printed webswhere the placement of the cut is continuously referenced against theprint on the web and the exact distance of web advance is adjustedaccordingly, in order to compensate for any irregularities in thelongitudinal spacing of the print patterns on the web and- /or forslippage that may occur on the circumference of the web-advancing feeddrum.

The present invention proposes to attain the above objective bysuggesting a novel device in which the circumference of the feed drum isslightly shorter or longer than the desired length of a cut printedblank, and where means are provided on the circumference of the feeddrum which are depressible under the pressure of a counter roller so asto temporarily increase or decrease the effective drum circumference inresponse to a measurement of the position of the printed pattern inrelation to the angular position of the cutting knife on the feed drum,as provided by a suitable monitoring unit.

Thus, the slightly undersized or over sized circumference of the feeddrum in relation to the distance between successive printed patterns onthe web will normally cause the printed blanks to be cut a small amounttoo short or too long, followed by a cumulative rearward shift orforward shift of the registration of the pattern in relation to thecutting knife, ifit were not for the arrangement of a controllablemomentary change in the effective feed drum circumference, by means ofwhich the length of the cut printed blank can be increased or decreased,in response to the actual position of the printed patterns on thecontinuous web, regardless of cumulative errors in the distance betweensuccessive printed patterns which may have been caused in the printingoperation or otherwise. This selective change in the effectivecircumference of the feed drum is obtained, according to the presentinvention, by providing on the feed drum a circumference portion whichis depressible radially, whereby the effective length of theweb-engaging drum circumference is changed as a function of the radialdepression. The distance over which the web is advanced during onerevolution of the feed drum is accordingly increased or decreased by agiven amount. The depression of the preferably resilient circumferentialportion of the feed drum is obtained by means of an adjustablypositioned counter roller which, for this purpose, is subjected to ashort, precisely timed approach motion, during which it is pressed morestrongly against the feed drum circumference. The counter rollerapproach motion is controlled by a print registration monitoring unitwhich operates in synchronism with the rotation of the cutting knife onthe feed drum and which signals any lag in the print registration on theendless printed web, as the latter is unwound from a supply roll. In apreferred embodiment of the invention, this print registrationmonitoring unit includes a photoelectric cell which responds to thepassage of certain reference marks on the printed web in front of thecell.

The novel device of the invention has the advantage of great simplicity,in that it utilizes the feed drum and the counter roller which arenormally used for the advancing of the printed web and for cutting itinto blanks, to perform the additional function of continuouslycompensating for variations in print registration. Thus, there are noadditional elements required over which the printed web has to run, andwhich would complicate the web guidance, possibly reducing theefficiency of the device, while increasing its tendency to operationalbreakdown. The suggested novel device, therefore, uses the previouslynecessary feed drum and counter roller combination, adding only adepressible circumference portion to the drum, and arranging the counterroller on a bearing support which permits a controlled approach motionof the counter roller against the feed drum.

In order to obtain this additional approach motion of the counter rolleragainst the feed drum, the invention further suggests, in a preferredembodiment, that the counter roller be journalled on a pivotabletumbling lever which is retainable in its normal position by means of asolenoid controlled latch pin and which, when the solenoid is energized,is pivoted under the influence of a tumbler spring, thereby approachingthe counter roller against the feed drum through the action of aneccentric. According to a further feature of the preferred embodiment ofthe invention, the opposite end of the tumbler lever carries a camfollower, cooperating with a disc cam rotating in synchronism with thefeed drum. This disc cam has an appropriately recessed circumferentialportion which permits the pivoting motion of the tumbler lever duringthe angular motion range in which the counter roller faces thedepressible circumference portion of the feed drum, while the remainingcircumference of the cam disc holds the cam follower and the tumblerlever to their normal position in which the latch pin can re-engage thelever. The result is an accurately timed approach motion of the counterroller against the feed drum. The distance of the approach motion isadjustable through an adjustment of the orientation of the eccentriccarrying the counter roller in relation to the tumbler lever. Thefrequency with which this corrective approach motion is executed isdetermined by the reading of the photoelectric cell.

The actual design of the feed drum with its compressible circumferenceportion may vary, depending upon the specific requirements ofapplication. Thus, the depressible surface portion may be in the form ofa resilient peripheral pressure cushion constituting a certaincircumference portion of the feed drum, the counter roller deforming thecushion locally in conformance with its curvature, as suggested in thepreferred embodiment of the invention. Alternatively, the depressiblecircumference portion may be provided in the form of a spring-biasedradially movable pressure piston, or in the form of a similarlyspring-biased, hinged pressure segment, occupying, for example, one-halfof the feed drum circumference. In this case, however, the normallyoversize drum circumference is selectively decreased.

In order to further enhance the accuracy of web advance, the preferredembodiment of the invention further suggests that in addition to thefeed drum and counter roller combination carrying the cutting knife,there be arranged ahead of them a second feed drum and counter rollercombination, the feed drum having again a depressible circumferenceportion and the counter roller being adapted for a similar selectiveapproach motion, controlled by a print registration monitoring unit.This duplication of the variable circumference web advancing featureproduces a more sensitive adjustment of the web advance, with theadditional advantage that the forces necessary for the unwinding andmovement of the printed web need not be produced by the feed drumcarrying the Cutting knife. Especially the irregularly occurringdeceleration forces are thereby kept away from the knife-carrying feeddrum. A spring-biased idler arranged between the two feed drums assuresan even web tension at the second feed drum.

The preferred embodiment of the invention, as mentioned, furtherprovides for a convenient adjustment of the distance of the approachmotion of the counter rollers from the normal position of their tumblerlevers, through a simple angular adjustment of the eccentric whichcarries the bearings of the counter rollers.

BRIEF DESCRIPTION OF THE DRAWINGS Further special features andadvantages of the invention will become apparent from the descriptionfollowing below, when taken together with the accompanying drawingswhich illustrate, by way of examples, several embodiments of theinvention, represented in the various figures as follows:

FIG. 1 shows in a schematic representation a mechanism configurationembodying the invention and corresponding to a side view thereof;

FIG. 2 shows a partial transverse section through the device of FIG. 1,the section being taken along line IIII thereof;

FIG. 3 shows a second version of a feed drum, as part of a modifiedembodiment of the invention; and

FIG. 4 shows a third version of the feed drum, as part of anothermodified embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The device of the invention,illustrated in FIG. 1 in a schematical manner only, is designed for thecutting of a continuous printed web 1 which is unwound from a supplyroll 2. The unwinding and advance of web 1 is obtained by means of twopairs of cooperating rollers, each pair consisting of a feed drum 3 or3a and of a counter roller 4 or 4a, respectively. The web portionrunning between the two roller pairs is engaged by an idler 5. Thelatter is mounted on a pivotable idler lever 6 and biased by a tensionspring 7 which maintains a constant web tension between the two rollerpairs, regardless of variations in web length.

The feed drum 3 of the second roller pair is equipped with a cuttingknife 8 arranged on its periphery, the knife 8 cooperating with thecounter roller 4 so as to cut a single blank from the printed web 1during each drum revolution. Each cut blank carries the same printedpattern. This roller pair thus not only advances the web 1, but alsocuts it into a series of printed blanks. The latter may be labels,package blanks, or the like, especially blanks for soft packages ofcigarettes.

In the embodiment shown in FIG. 1, each of the two feed drums 3 and 3ahave on one portion of the periphery a resiliently compressible cushion9 which represents a depressible circumference portion of the feed drum.The counter roller 4 or 4a, respectively, which cooperates with thisdepressible circumference portion and with the remaining periphery ofthe feed drum to advance the printed web 1, is supported on a tumblerlever 10 or 10a, respectively, the lever being pivotable between anormal position in which the roller pair advances a web length equal to3.14 times the diameter of the feed drum, and an approach position inwhich the counter roller 4 or 4a, presses into the peripheral cushion 9or drum 3 or 30, respectively. The two tumbler levers l0 and 10a arebiased toward this approach position by means of tension springs 11 and11a, respectively, the levers being selectively held in their normalposition by means of a trigger mechanism. This trigger mechanismconsists of a latch pin 12 controlled by a solenoid 13, as shown in FIG.2. There, it can be seen that, when the solenoid 13 is energized, itretracts the latch pin 12 from the tumbler lever 10, allowing the latterto make its approach motion.

The timing, duration, and distance of the approach motion of the counterrollers 4 and 4a against their cooperating feed drums 3 and 3a, asdetermined by the pivoting motion of the tumbler levers l0 and 10a, arecontrolled by means of a cam follower 14 arranged on the tumbler leverand engaging a disc cam 15 rotating in synchronism with the feed drums 3and 3a. The disc cam 15 has on its periphery a recessed cam portion ordepression 16 into which the cam follower 14 can descend for theapproach motion of the tumbler lever. The depression 16 of the disc cam15 thus determines both the timing and the distance of the approachmotion of the counter roller 4 against the peripheral cushion 9, if anapproach motion has been triggered by the solenoid 13.

The two feed drums 3 and 3a have a diameter which gives them acircumference which is just slightly smaller than the circumferencewhich would be needed to advance the printed web 1 from one printedpattern to the next. Thus, when the web 1 is so positioned that thecutting knife 8 cuts a printed blank at the proper registration, thenext cut will produce a slightly short cut blank, unless the effectivecircumference of the feed drum is corrected to produce a slightly longcut blank. Such a circumference correction is obtained through theapproach motion of the counter rollers 4 and 4a against thecircumferential cushions 9 of the feed drums 3 and 3a, respectively,whereby the effective circumference on the feed drums is temporarilyincreased to a length which is just slightly greater than the distancebetween two printed patterns on web 1, thereby reducing or eliminatingany lag of the printed web 1 in relation to the cutting knife 8. Theincrease in the effective circumference of the feed drum is obtainedthrough the depression of its peripheral cushion 9 under the approachmotion of the counter roller, which thereby impresses its smallercurvature into the cushion 9 and produces a sinuous curvature ofmomentarily increased length, so that an additional small increment ofweb length is advanced between the roller pair.

As mentioned, the approach motion of the counter rollers 4 and 4a is notperformed during each revolution of the feed drums 3 and 30, but istriggered selectively, whenever the printed web 1 lags behind thecutting knife 8. That condition is monitored by means of a printregistration monitoring unit, consisting essentially of a photoelectriccell 17 which, at a given angular position of the feed drum 3, verifiesthe position of a reference mark on the printed web 1. If that mark isin the proper place, or slightly ahead, the photoelectric cell will notrespond. Inthis case, no approach motion between the roller pair willoccur, because the latch pin 12 retains the tumbler lever in its normalposition. But, if the photoelectric cell 17 finds the reference mark onthe printed web 1 lagging behind, it will trigger the solenoid 13 toretract the latch pin 12, thereby releasing the tubler lever 10 to bepivoted under the influence of the tumbling spring 1], when the camfollower 14 reaches the depression 16 of the disc cam 15. Thiscircumference correction on the feed drums is repeated, if necessary,for a number of consecutive *long" cuts, so that the position of theprinted pattern on the continuously running web 1 advances to itsdesired position. at'which point the photoelectric cell 17 no longertriggers the corrective approach motion. Since the tumbler levers 10 and10a are maintained in their normal position during a major portion ofeach revolution, the latch pin 12, when released by the solenoid 13,will reengage the tumbler lever 10, as soon as the corrective advance isno longer required. The latch pin 12 then remains engaged, until thephotoelectric cell 17 signals a new lag of the web 1. Thus, the deviceof the invention will alternatingly produce a series of slightly shortcut blanks, followed by a series of slightly long cut blanks. with theprinted pattern accurately registered on the blanks.

The disc earns and their cooperating cam followers 13 determine, duringeach revolution, both the exact timing and the displacement of theapproach motion of the counter rollers on the tumbler levers 10 and 10a,respectively. Obviously, this approach motion must coincide with theangular position of the peripheral cushion 9 against the counterrollers. Thus, both the timing and the distance of the approach motioncan be adjusted by replacing the disc cam 15 with a cam having adifferent depression 16. On the other hand, the position of the counterrollers 4 and 4a is also adjustable in relation to their feed drums 3and 30. by adjusting the orientation of the eccentrics on which they arejournalled in relation to the tumbler levers l0 and 100, respectively.

The the arrangement of FIG. 1 illustrates a second photoelectric cell17a controlling the first roller pair 3a, 4a. Alternatively, the firstroller pair may be replaced by a variable-speed advancing device whosespeed is adjusted in response to the web tension ahead of the cutterfeed drum 3, as reflected by the position of the spring-biased idler 5.

The depressible peripheral cushion 9 of the feed drums 3 and 3a ispreferably of a resilient compressible material, such as rubber,occupying a portion of the drum circumference. However, alternativedepressible circumference portions may be provided on the feed drums, asshown in FIGS. 3 and 4, for example. Here, a solid, radially biasedmember of metal or plastic material forms a portion of the drumcircumference. In FIG. 3, the depressible member is a pressure piston 18which is normally held in alignment with the periphery of drum 3 bymeans of a compression spring 19, against which it is depressible underthe approach motion of the counter roller (not shown). In the embodimentof FIG. 4, the depressible member is a pressure segment 20 which ishinged to the drum 3 on one of its extremities and biased radiallyoutwardly by a spring 21 on its opposite extremity. Again, an approachmotion of the counter roller depresses the segment 20 radially inwardly,thereby temporarily decreasing the effective circumference of the feeddrum. Obviously, in this case, as in the case of the pressure piston ofFIG. 3, the print registration monitoring unit responds to a leaddeviation of a reference mark, rather than to a lag deviation, theentire operation being otherwise identical.

It should be understood, of course, that the foregoing disclosuredescribes only preferred embodiments of the invention and that it isintended to cover all changes and modifications of these examples of theinvention which fall within the scope of the appended claims.

I claim:

1. In an apparatus for cutting a continuous web, having regularly spacedprinted patterns or other readable markings thereon, into a series ofblanks whose cuts are positioned substantially at the same distance withreference to the printed pattern, regardless of cumulative deviations inthe web advance and/or in the pattern spacing on the web, a device forvarying the web advance per cutting cycle in reference to the positionof the printed pattern on the web, the device comprising in combination:

a pair of web advancing rollers, engaging the printed web from oppositesides, one roller being a feed drum, rotating at constant speed, theother roller serving as a counter roller;

a radially oriented cutting knife on the periphery of the feed drum,cutting the web once during each drum revolution so as to obtain, witheach cut, a printed blank of a length corresponding to the circumferenceof the feed drum;

a deformable circumference portion on the feed drum defined by aradially depressible member of the feed drum;

a circumference on the feed drum with, in the absence of deformation ofsaid circumference portion, advances a blank length which is slightlyless than the distance at which the printed patterns are spaced on theweb;

means for forcibly approaching the counter roller against the feed drumduring that angle of drum revolution in which the roller faces thedeformable circumference portion of the drum, thereby depressing saidmember of the drum and temporarily increasing its effectivecircumference, so as to advance a blank length which is longer than thatwhich would be advanced without such depression; and

means for selectively controlling the approaching means to execute, ornot to execute, said approach motion during any given drum revolution,in response to the position of the printed pattern on the web inrelation to the angular position of the cutting knife on the drum.

2. A device as defined in claim 1, wherein:

the counter roller approaching means includes a pivotable tumbler levercarrying the counter roller at a small distance from the pivot center ofthe lever, and a tumbler spring engaging said lever, the latter beingpivotable between a normal position in which the counter rollercooperates with the feed drum without depressing its depressible member,and an approach position in which said depression takes place; saidspring biasing the tumbler lever toward its approach position; and

the approach controlling means is a means for selectively blocking thetumbler lever from executing the counter roller approach motion.

3. A device as defined in claim 2, wherein the counter rollerapproaching means further includes means for holding the tumbler leverin its normal position, against the tumbler spring, during that angle ofdrum revolution in which the counter roller does not face the deformablecircumference portion of the feed drum.

4. A device as defined in claim 2, wherein the counter rollerapproaching means further includes:

a cam follower carried by the tumbler lever;

a control cam arranged for synchronous rotation with the feed drum andengaging the cam follower in a one-way engagement in opposition to thetumbler spring;

a circular high section on the control cam holding the tumbler lever inits normal position, against the tumbler spring, during that angle ofdrum revolution in which the counter roller does not face the deformablecircumference portion of the drum; and

a low cam section which, when the blocking means is inoperative, allowsthe tumbler lever to execute the approach motion to the approachposition, and back, the motion force being provided by the tumblerspring and the displacement being determined by the cam surface.

5. A device as defined in claim 4, wherein the tumbler lever blockingmeans includes:

a retractable blocking element which is normally positioned in the wayof the tumbler lever so as to prevent it from executing an approachmotion;

a spring biasing the blocking element against retraction;

a solenoid which, when energized, retracts the blocking member; and

means for selectively energizing the solenoid in response to theposition of the printed pattern on the web in relation to the angularposition of the cutting knife on the feed drum.

6. A device as defined in claim 5, wherein the solenoid energizing meansincludes a photoelectric cell which is arranged to read a reference markof each printed pattern on the moving web, at a given angular positionof the cutting knife on the feed drum, and in response to its reading,to initiate energization of the solenoid, if the position of saidreference mark is behind its normal position.

7. A device as defined in claim 2, wherein in relation to a givenpivoting angle of the tumbler lever between said two positions, the twocorresponding positions of the counter roller are adjustable both interms of motion distance and of the distance of its end positions fromthe feed drum, by an. adjustable eccentric arranged on the tumbler leveron which the counter roller is journalled. 8. A device as defined inclaim 1, wherein the radially depressible member of the feed drum whichdefines the deformable circumference portion is a resilientlycompressible pressure cushion which, in its non-compressed state, formsa part of a regular cylindrical outline of the feed drum.

9. A device as defined in claim 1, wherein the radially depressiblemember of the feed drum which defines the deformable circumferenceportion is a radially guided pressure piston and includes a compressionspring biasing the piston outwardly against'an abutment, the pistonforming in its abutted position a part of a regular cylindrical outlineof the feed drum.

10. A device as defined in claim 1, wherein the radially depressiblemember of the feed drum which defines the deformable circumferenceportion is a pressure segment which is pivotably attached to the feeddrum and includes a spring biasing the segment outwardly against anabutment, the segment forming in its abutted position a part of aregular cylindrical outline of the feed drum.

1 l. A device as defined in claim 1, further comprising means forfeeding the printed web to the pair of web advancing rollers at avariable speed, adjusted in response to the web tension exerted by saidroller pair.

12. A device as defined in claim 1, further comprising means for feedingthe printed web to the pair of web advancing rollers at a variablespeed, adjusted in response to the position of the printed pattern onthe web.

13. A device as defined in claim 12, wherein:

the web feeding means includes a second, similar pair of web advancingrollers, the feed drum and counter roller being substantially the sameas those of the first-mentioned roller pair, but for the absence of acutting knife on the second feed drum; and

the second roller pair is similarly combined with counter rollerapproaching means and selective approach controlling means, respondingto the position of the printed pattern on the web in relation totheangular position of the second feed drum.

14. A device as defined in claim 13, wherein the web feeding meansfurther includes an idler on a spring-loaded pivot arm for establishingan even web tension between the web advancing roller pair and the webcutting roller pair.

1. In an apparatus for cutting a continuous web, having regularly spacedprinted patterns or other readable markings thereon, into a series ofblanks whose cuts are positioned substantially at the same distance withreference to the printed pattern, regardless of cumulative deviations inthe web advance and/or in the pattern spacing on the web, a device forvarying the web advance per cutting cycle in reference to the positionof the printed pattern on the web, the device comprising in combination:a pair of web advancing rollers, engaging the printed web from oppositesides, one roller being a feed drum, rotating at constant speed, theother roller serving as a counter roller; a radially oriented cuttingknife on the periphery of the feed drum, cutting the web once duringeach drum revolution so as to obtain, with each cut, a printed blank ofa length corresponding to the circumference of the feed drum; adeformable circumference portion on the feed drum defined by a radiallydepressible member of the feed drum; a circumference on the feed drumwith, in the absence of deformation of said circumference portion,advances a blank length which is slightly less than the distance atwhich the printed patterns are spaced on the web; means for forciblyapproaching the counter roller against the feed drum during that angleof drum revolution in which the roller faces the deformablecircumference portion of the drum, thereby depressing said member of thedrum and temporarily increasing its effective circumference, so as toadvance a blank length which is longer than that which would be advancedwithout such depression; and means for selectively controlling theapproaching means to execute, or not to execute, said approach motionduring any given drum revolution, in response to the position of theprinted pattern on the web in relation to the angular position of thecutting knife on the drum.
 2. A device as defined in claim 1, wherein:the counter roller approaching means includes a pivotable tumbler levercarrying the counter roller at a small distance from the pivot center ofthe lever, and a tumbler spring engaging said lever, the latter beingpivotable between a normal position in which the counter rollercooperates with the feed drum without depressing its depressible member,and an approach position in which said depression takes place; saidspring biasing the tumbler lever toward its approach position; and theapproach controlling means is a means for selectively blocking thetumbler lever from executing the counter roller approach motion.
 3. Adevice as defined in claim 2, wherein the counter roller approachingmeans further includes means for holding the tumbler lever in its normalposition, against the tumbler spring, during that angle of drumrevolution in which the counter roller does not face the deformablecircumference portion of the feed drum.
 4. A device as defined in claim2, wherein the counter roller approaching means further includes: a camfollower carried by the tumbler lever; a control cam arranged forsynchronous rotation with the feed drum and engaging the cam follower ina one-way engagement in opposition to the tumbler spring; a circularhigh section on the control cam holding the tumbler lever in its normalposition, against the tumbler spring, during that angle of drumrevolution in which the counter roller does not face the deformablecircumference portion of the drum; and a low cam section which, when theblocking means is inoperative, allows the tumbler lever to execute theapproach motion to the approach position, and back, the motion forcebeing provided by the tumbler spring and the displacement beingdetermined by the cam surface.
 5. A device as defined in claim 4,wherein the tumbler lever blocking means includes: a retractableblocking element which is normally positioned in the way of the tumblerlever so as to prevent it from executing an approach motion; a springbiasing the blocking element against retraction; a solenoid which, whenenergized, retracts the blocking member; and means for selectivelyenergizing the solenoid in response to the position of the printedpattern on the web in relation to the angular position of the cuttingknife on the feed drum.
 6. A device as defined in claim 5, wherein thesolenoid energizing means includes a photoelectric cell which isarranged to read a reference mark of each printed pattern on the movingweb, at a given angular position of the cutting knife on the feed drum,and in response to its reading, to initiate energization of thesolenoid, if the position of said reference mark is behind its normalposition.
 7. A device as defined in claim 2, wherein in relation to agiven pivoting angle of the tumbler lever between said two positions,the two corresponding positions of the counter roller are adjustableboth in terms of motion distance and of the distance of its endpositions from the feed drum, by an adjustable eccentric arranged on thetumbler lever on which the counter roller is journalled.
 8. A device asdefined in claim 1, wherein the radially depressible member of the feeddrum which defines the deformable circumference portion is a resilientlycompressible pressure cushion which, in its non-compressed state, formsa part of a regular cylindrical outline of the feed drum.
 9. A device asdefined in claim 1, wherein the radially depressible member of the feeddrum which defines the deformable circumference portion is a radiallyguided pressure piston and includes a compression spring biasing thepiston outwardly against an abutment, the piston forming in its abuttedposition a part of a regular cylindrical outline of the feed drum.
 10. Adevice as defined in claim 1, wherein the radially depressible member ofthe feed drum which defines the deformable circumference portion is apressure segment which is pivotably attached to the feed drum andincludes a spring biasing the segment outwardly against an abutment, thesegment forming in its abutted position a part of a regular cylindricaloutline of the feed drum.
 11. A device as defined in claim 1, furthercomprising means for feeding the printed web to the pair of webadvancing rollers at a variable speed, adjusted in response to the webtension exerted by said roller pair.
 12. A device as defined in claim 1,further comprising means for feeding the printed web to the pair of webadvancing rollers at a variable speed, adjusted in response to theposition of the printed pattern on the web.
 13. A device as defined inclaim 12, wherein: the web feeding means includes a second, similar pairof web advancing rollers, the feed drum and counter roller beingsubstantially the same as those of the first-mentioned roller pair, butfor the absence of a cutting knife on the second feed drum; and thesecond roller pair is similarly combined with counter roller approachingmeans and selective approach controlling means, responding to theposition of the printed pattern on the web in relation to the angularposition of the second feed drum.
 14. A device as defined in claim 13,wherein the web feeding means further includes an idler on aspring-loaded pivot arm for establishing an even web tension between theweb advancing roller pair and the web cutting roller pair.